Tac: Will help give you monster damage and eat through your enemies faster than the other types.

Eng: WIll boost the relatively small durability of Escorts much higher than it naturally is, along you to stay in the fight longer and keep dishing out the damage.

Sci: Nice mix of both; Sensor Scan will boost your damage, and Dampening Field will give you a great resistance buff. You also get Photonic Fleet to cause some disruption/boost your damage and SNB to strip buffs and resistances away from your target. SciFleet is also a huge shield resistance buff.

As far as traits, you definitely want Elusive and Accurate. The other two are up to you. I recommend Efficient, however.